Underground Blasting

[Music] the use of explosives in the mining industry has always been a potentially hazardous business hey Dave let's go ahead and drill that next H out well you better check it check that boot like be sure I'd hold CL n forget it go ahead and drow it [Music] out the first priority of the mining industry must always be the health and safety of the miners every effort should be made to avoid blasting accidents charting what happen little best we to understand Keith was standing right here shoving out for his snake hole David had just got through drilling that hole there and he moved up to this one here and when Keith evidently raised up it loow him over and his head would land right there and his feet would land up here you know Charlie miners have been told time and time again not to drill in boot legs well there's one guy that could drill in anymore the fact is blasting materials today are safer and more controllable than ever before why should needless ACC acents continue to occur gentlemen we're Gathering here an attempt to gather the fact in examining blasting accidents the answer seems clear the vast majority are caused by violations of one or more explosive safety regulations some drawings that were sketched at the scene of the accident the although records show that violations and accidents occur in transportation and storage it is in the use of explosives that most fatalities and injuries occur underground mining in metal and non-metal operations covers a wide variety of ore and geological conditions shot sizes and drilling angles for this reason blast plans are established and should be followed as closely as [Music] possible while each operation is responsible for establishing its own specific procedures there are some basic safety procedures that should always be followed when blasting these procedures fall into four categories drilling loading detonation and post blast examination let's look at each step to see how accidents can be [Music] prevented before drilling actually begins loose material should be barred [Music] down regulations state that the area must be inspected for hazards one of the hazards could be undetonated explosives the area should be thoroughly examined for evidence of misfires if undetonated explosives or detonators are discovered they should be reported to the proper supervisor and should be disposed of before other work is performed in the area in addition to visual observations blasting galvanometers should be used to test for continuity and resistance on any electric blasting cap wires that are found only when you are convinced that the area is free from misfires and other hazards should drilling begin drilling pattern calculations can be quite complex they include various elements that will assure a good blast with minimum Hazard the number depth spacing and angle of the bore holes must be considered as well as the amount and type of explosives and detonators as each hole is completed it should be checked for obstructions before moving on to the next often the only inspection tool a driller has is the drill itself with experience the driller develops a feel for the grill steel as he removes [Music] it when all holes appear to be properly drilled and in good shape the next step May [Music] [Music] begin the choice of explosives and detonators like the blast PL is a decision based on a number of variables technology is providing safer more controllable blasting products but these new products like older ones must be handled properly to ensure [Music] safety when transporting explosives only the amount required for a particular blast should be brought to the site [Music] if electric blasting caps are used all electrically operated equipment within 50 ft of bore holes containing electric blasting caps should be deenergized okay [Music] than stray current test should be conducted the maximum tolerable stray current is 005 amps through a 1 ohm resistor loading should begin as close as possible to blasting time a tamping pole made of non-sparking material is used to test for obstructions the hole punch too should be made of non-sparking material the primer should always be prepared immediately prior to loading it into the drill hole the electric blasting cap should be inserted deep within the cartridge to help in preventing it from being accidentally pulled out for further protection the cap lead should be firmly tied around the cartridge to minimize the possibility of misfires the primer cartridge should be loaded with the cap pointing toward the collar [Music] the primer should never be tamped directly but should have one or more cartridges between it and the tamping pole to act as a cushion usually two or three light blows are sufficient to produce good compaction sometimes a steady push is all that's needed with experience the loader will develop the field for proper [Music] tapping once charging operations have been completed all unused explosives and detonators should be removed to a safe [Music] location special precautions should be taken in mines employing pneumatic loading powder being blown through the hose can cause a buildup of an electrostatic charge which can cause initiation of both electrical and non-electrical detonators okay it is essential therefore to dissipate this buildup of static electricity the hose must be semiconductive and proper grounding of equipment is extremely [Music] important lightning can detonate electric blasting caps below the ground as well as above for distances up to several miles if an electrical storm is detected while blasting electrical charging shall be suspended in shaft sinking tunneling and other operations telephone call for Larry Hello Larry yeah Harry an electrical storm will hit here in about 10 minutes get your blasters out of the face area bad lightning storm be here in about 10 minutes I'll tell them all Personnel shall be withdrawn to a safe location within the [Music] mine one more hey fellas I just got a call from upstairs and there's a bad storm coming so we better shut this stuff up if you're not you ready we'll get out of here for a while good luck take [Music] right the use of electric blasting caps requires that resistance and continuity tests must be [Music] made accident data show that a variety of instruments have been used to conduct these tests some have had the sufficient current to set off the [Music] charge only approved blasting galvanometers or instruments designed for testing electric blasting caps should be used to test blasting circuits and components of course blasting lines must be kept shutted except when being tested until immediately before [Music] [Music] blasting loading and testing according to approved procedures is the best way to assure a proper blast and the elimination of misfires and their [Music] hazards yeah we have reached the most critical step in the entire blasting process [Music] detonation explosive should always be handled by experienced miners or other under their direct supervision it is especially important in this stage that only authorized individuals be involved say we do this about you up Corner Char on get ready off okay having one person in charge eliminates communication problems that can cause confusion and accident regulations require that the blast area be barricaded posted flagged or guarded against unauthorized entry pre-arranged Tim taes and signals must be completely understood this is especially important in underground mining where visibility is limited all persons must be cleared and removed from areas endangered by the blast and it is the guard's responsibility to allow no one to enter the blast area setting off a blast uper you have to hold up a minute consideration must be given to toxic fumes as well as the concussion and fly Rock when establishing safe [Music] distances once the pre-arranged blasting time has been reached ample warning must be given fire a hole fire a hole fire aole [Music] immediately after a blast smoke dust and toxic fumes fill the site creating a hazardous condition under no circumstances should anyone be allowed to re-enter the area until it has cleared after the smoke and fumes have cleared and the roof has been inspected faces and muuk piles should be thoroughly examined for undetonated explosives look for powder wires or other evidence of misfires electric blasting cap leg wires should be tested with a blasting galvanometer evidence of misfire should be reported to the proper supervisor and any undetonated explosives disposed of before other work is performed in the area it must be understood that blasting is an art okay hold it an art that takes years of experience to master it is not uncommon to encounter unus usual situations that are not covered by established procedures oh we got blocked here if it should happen to you don't let your actions exceed your knowledge when lives are at stake you can't afford to count on guesses and if you have a question what we going to do about that CL ask for help we could load it on out well we could the Federal Regulations written by the Mind safety and health administration are not suggestion figure out what good they're the law their sole purpose is to protect you the steps outline follow Federal explosive safety regulations and apply to all underground mine blasting but each mine operation has its own unique conditions which may necessitate additional safety rules these as well as the Federal Regulations are designed for your benefit to keep you and your fellow miners from being involved in accidents remember Detonator should be securely embedded and properly directed within the cartridge proper placement of the primer in the bore hole and careful handling of the blasting leads will also reduce the number of misfires it is especially important to remember that injuries and deaths can be greatly reduced by properly clearing posting and guarding all blasts sites and by using clearly defined Communications fire Theo fire theole fire and ample warning [Music] signals if every minor complied with these regulations the great majority of blasting related accidents could be [Music] avoided [Music] oh